The present invention relates to a device for preparing, measuring, and dispensing a cosmetic product, particularly a product for dyeing or bleaching hair, obtained by mixing two liquid, cream, or gel components immediately prior to use.
In the following, reference will be made essentially to products for dyeing but it is understood that the explanations provided apply equally to products for bleaching.
Proper utilization of dyeing products, usually formed by mixing two components, the oxidizer and the dye, depends largely on the quality of mixing of the two components immediately before application to the hair.
Now, these two components are of very different natures and structures.
The oxidizer, which is generally in liquid or cream form, poses no particular storage problem and is often packed in multidoses in plastic, particularly polyethylene, bottles.
The dye, which is generally liquid, cream, or gel, is very sensitive to oxidation by ambient air, is affected by ultraviolet radiation, and is particularly reactive to metals and metal salts.
The dye is thus usually packaged in hermetic containers, protected from light and air, particularly in the form of a single-use tube, usually made of aluminum, coated on the inside with a varnish or a multilayer protective film.
To decrease costs, the use of multidose cans, particularly of the aerosol type provided with a valve dispensing mechanism, has also been proposed.
When the dye is highly liquid, the dye and oxidizer may be mixed in a container with a transparent wall provided with graduations into which first the oxidizer then the dye is poured, each up to a predetermined graduation mark, to obtain a measured mix.
Special problems arise, however, if the dye is in the form of a cream or gel. If the dye is poured before the oxidizer into the mixing container, mixing is poor and it is not possible to measure simply by reading the level.
If the dye is poured into the oxidizer, the dye, which is less dense, floats on the oxidizer like an iceberg and substantial measuring errors, on the order of 10%, occur and have injurious consequences for the hair-dyeing result.
Hence, the proposal was made in FR-A-2,429,038 of using a transparent container for mixing the components, provided with graduations on its wall, and having an automatically closing valve on its bottom through which the two components, namely the oxidizer and the dye, are introduced in succession, each up to a given graduation mark.
Such a container has, however, the drawback that the permanent presence of a valve in the bottom of the container makes it very difficult to remove any remaining product after utilization.
It is very important to avoid admixing dyes or tints to avoid unpleasant surprises in the result obtained, particularly when a very dark dye is followed by a very light dye on two consecutive heads of hair.
Designing the valve is also complex because it is essential for it to be able to operate only in the direction in which the components enter the mixing container from the outside to the inside, so that the valve must be designed to close positively and not merely passively, without including any metal components or having only metal components that are provided with a coating, particularly a protective varnish.